This invention relates to an apparatus for making a fiber lap from fiber tufts and feeding the fiber lap to a fiber processing machine such as a card, a roller card unit, a beater or the like. The feeder has a reserve chute receiving pneumatically conveyed fiber tufts and a feed chute receiving fiber tufts from the reserve chute. In the feed chute the fiber tufts are compressed by a fan-generated compressing air stream. The feed chute contains a pressure sensor which, by means of a pressure regulator, is connected with the controllable drive of a feed roller which advances fiber tufts from the reserve chute to the feed chute.
In order to be able to compress relatively large fiber tufts with a relatively small air resistance, a fan with a relatively large output is required. If in the same tuft feeder easily compressible fibers are to be processed, and particularly when the feeder is to operate alternately with two types of fiber tufts, according to prior art arrangements at the beginning of the fiber processing operation, the setting of the pressure sensor responding to the pressure in the feed chute is manually altered. The pressure sensor is connected by means of a regulator with the drive motor of the feed roller of the tuft feeder whereby the quantity of the fiber material supplied from the reserve chute to the feed chute is varied. In such an operational mode the fill-height (fill-level) of the fiber tuft column in the feed chute varies which also changes the extent to which fiber material covers the air outlet openings in the feed chute. It is a disadvantage of this arrangement that the actual fill-height deviates from a fill-height or a coverage of the air outlet openings by the fiber tufts which is optimal for the compression of the fiber tuft column in the feed chute.